Comparison of Seasonal Flow Rate Change Indices Downstream of Three Types of Dams in Southern Quebec (Canada)
Round 1
Reviewer 1 Report
This paper aims to analyze the impacts of dam management methods on seasonal daily flow variability in Quebec. Overall, I would not consider this paper as innovative. It is mostly a case study to analyze seasonal flow rate changes due to different type of dam operations.
(1) I do not quite agree with the authors’ statement that there have been no studies on seasonal flow rate change (Line 46). In fact, there are a number of studies on this topic. Here are a few examples:
- Gebremicael, T. G., Y. A. Mohamed, P. Van Zaag, and E. Y. Hagos. "Temporal and Spatial Changes of Rainfall and Streamflow in the Upper Tekeze-Atbara River Basin, Ethiopia." Hydrology and Earth System Sciences 21, no. 4 (Apr 2017): 2127-42.
- Haas, N. A., B. L. O'Connor, J. W. Hayse, M. S. Bevelhimer, and T. A. Endreny. "Analysis of Daily Peaking and Run-of-River Operations with Flow Variability Metrics, Considering Subdaily to Seasonal Time Scales." Journal of the American Water Resources Association 50, no. 6 (Dec 2014): 1622-40.
- Li, D. N., D. Long, J. S. Zhao, H. Lu, and Y. Hong. "Observed Changes in Flow Regimes in the Mekong River Basin." Journal of Hydrology 551 (Aug 2017): 217-32.
- Mori, T., Y. Onoda, and Y. Kayaba. "Geographical Patterns of Flow-Regime Alteration by Flood-Control Dams in Japan." Limnology 19, no. 1 (Jan 2018): 53-67.
- Penas, F. J., and J. Barquin. "Assessment of Large-Scale Patterns of Hydrological Alteration Caused by Dams." Journal of Hydrology 572 (May 2019): 706-18.
(2) The authors state that their second study objective is to determine the influence of dam management methods on the relationship between flow rate change and climate (temperature and precipitation) (L69-71). First of all, I could not see the significance of this study objective. Secondly, I am wondering whether the authors have chosen the suitable climate variables to correlate with seasonal flow variability. For example, can rainfall variability be a better variable to use than total amount of rainfall? Thirdly, the authors merely make comparison among three dams of their choice, whose data availability and watershed characteristics are also different. Could they extrapolate the results to the general conclusion that dam management has little effect on the relationship between the two seasonal flow rate change indices and climate (Line 448-449)?
(3) The authors tend to draw conclusions that are not adequately supported by their analysis results. For example, the authors conclude that downstream increased seasonal flow rate change can generate impacts similar to those caused by increased daily flow rate change (Line 459-461). I could not see how their analysis results could corroborate this statement.
(4) I suggest the manuscript should be carefully proofread, since there are a number of minor errors throughout the paper. For example:
- Line 154 natural rivers downstream of dams ?
- Line 170-171 that is follows model (3),
- Equation (1) and (5)
(5) I suggest the authors put tables and figures close to their related text so that it is easier for readers to follow their discussions.
(6) Many paragraphs are quite long in the manuscript. I suggest the authors divide them into shorter ones so that it is easier for readers to follow their discussions.
(7) Line 388-389 The authors state that the influence of dam management methods also affects the temporal variability of the two seasonal flow rate change indices. Nevertheless, discussions in the rest of the paragraph are not related to dam management?
(8) Overall, I feel the paper somewhat lacks depth in its analysis and discussion. Compared to current results, I suggest a more interesting research question to address is to quantify the relative importance of dam operations and climate change in their impacts on historical flow variability.
Author Response
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REVIEWER # 01 : RESPONSES TO COMMENTS
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We would like to extend our sincere thanks to the reviewer whose comments and suggestions have significantly contributed to improving the content of our manuscript.
The corrections made are highlighted in yellow in the revised manuscript.
Comment #01
This paper aims to analyze the impacts of dam management methods on seasonal daily flow variability in Quebec. Overall, I would not consider this paper as innovative. It is mostly a case study to analyze seasonal flow rate changes due to different type of dam operations.
(1) I do not quite agree with the authors’ statement that there have been no studies on seasonal flow rate change (Line 46). In fact, there are a number of studies on this topic. Here are a few examples:
- Gebremicael, T. G., Y. A. Mohamed, P. Van Zaag, and E. Y. Hagos. "Temporal and Spatial Changes of Rainfall and Streamflow in the Upper Tekeze-Atbara River Basin, Ethiopia." Hydrology and Earth System Sciences 21, no. 4 (Apr 2017): 2127-42.
- Haas, N. A., B. L. O'Connor, J. W. Hayse, M. S. Bevelhimer, and T. A. Endreny. "Analysis of Daily Peaking and Run-of-River Operations with Flow Variability Metrics, Considering Subdaily to Seasonal Time Scales." Journal of the American Water Resources Association 50, no. 6 (Dec 2014): 1622-40.
- Li, D. N., D. Long, J. S. Zhao, H. Lu, and Y. Hong. "Observed Changes in Flow Regimes in the Mekong River Basin." Journal of Hydrology 551 (Aug 2017): 217-32.
- Mori, T., Y. Onoda, and Y. Kayaba. "Geographical Patterns of Flow-Regime Alteration by Flood-Control Dams in Japan." Limnology 19, no. 1 (Jan 2018): 53-67.
- Penas, F. J., and J. Barquin. "Assessment of Large-Scale Patterns of Hydrological Alteration Caused by Dams." Journal of Hydrology 572 (May 2019): 706-18.Response
We have edited the text in line 46 and added these references in our article.
Comments #02
(2) The authors state that their second study objective is to determine the influence of dam management methods on the relationship between flow rate change and climate (temperature and precipitation) (L69-71). First of all, I could not see the significance of this study objective. Secondly, I am wondering whether the authors have chosen the suitable climate variables to correlate with seasonal flow variability. For example, can rainfall variability be a better variable to use than total amount of rainfall? Thirdly, the authors merely make comparison among three dams of their choice, whose data availability and watershed characteristics are also different. Could they extrapolate the results to the general conclusion that dam management has little effect on the relationship between the two seasonal flow rate change indices and climate (Line 448-449)?
Responses
1. We have clarified the second objective and added a third objective.2. We were unable to have daily temperature and precipitation data to calculate their seasonal variability. Therefore, we used mean temperature and total amount of precipitation. These data are available so can be easily used.3. Other studies that we have already published on the impacts of dams on other flow characteristics fully justify the extrapolation of our results to other dams characterized by the same management methods in Quebec.
Comment #03
(3) The authors tend to draw conclusions that are not adequately supported by their analysis results. For example, the authors conclude that downstream increased seasonal flow rate change can generate impacts similar to those caused by increased daily flow rate change (Line 459-461). I could not see how their analysis results could corroborate this statement.
Response
We replaced “can” with “could” thus formulating an assumption which should be checked later.
Comment #04
(4) I suggest the manuscript should be carefully proofread, since there are a number of minor errors throughout the paper. For example:
- Line 154 natural rivers downstream of dams ?
- Line 170-171 that is follows model (3),
- Equation (1) and (5)Response
We fixed these minors errors.
Comment #05
(5) I suggest the authors put tables and figures close to their related text so that it is easier for readers to follow their discussions.
Response
This is a layout designed by the journal to avoid empty spaces in the article.
comment #06
(6) Many paragraphs are quite long in the manuscript. I suggest the authors divide them into shorter ones so that it is easier for readers to follow their discussions.
Response
The discussion is subdivided according to the three objectives defined in the introduction
Comment #07
(7) Line 388-389 The authors state that the influence of dam management methods also affects the temporal variability of the two seasonal flow rate change indices. Nevertheless, discussions in the rest of the paragraph are not related to dam management?
Response
We have modified this sentence to make it consistent with the rest of the paragraph
Comment #08
(8) Overall, I feel the paper somewhat lacks depth in its analysis and discussion. Compared to current results, I suggest a more interesting research question to address is to quantify the relative importance of dam operations and climate change in their impacts on historical flow variability.
Response
We have reformulated the last two study objectives to respond to this criticism. It is important to note that we are not analyzing the impacts of climate on the temporal variability of flow rate change indices but the influence of management methods on the relationship between these indices and climate variables. This subject is different from that already studied in other works (e.g., Li et al., 2017).
Author Response File: 
Author Response.pdf
Reviewer 2 Report
I cannot judge the quality of the statistics, but they look well-developed.
My hesitance about the significance of the manuscript is because I fail to see the added value of this study. It merely seems to statistically confirm that, roughly spoken, dams cause a reduction in flow variability, something that was already widely known. The introduction suggests that the study can contribute to a better understanding of the ecological impacts of dams. The final conclusion that operational management is of influence on the flow variability is in that light very, very meagre.
Overall, the manuscript fails to show that the study brings new insights that are of use for "restoring the ecological integrity of regulated rivers".
Author Response
REVIEWER # 02 : RESPONSES TO COMMENTS
We thank the reviewer for his comments and suggestions.
The corrections made are highlighted in yellow in the revised manuscript.
Comment #01
I cannot judge the quality of the statistics, but they look well-developed.
My hesitance about the significance of the manuscript is because I fail to see the added value of this study. It merely seems to statistically confirm that, roughly spoken, dams cause a reduction in flow variability, something that was already widely known.
Response
Our study clearly shows that the impacts of dams on flow variability largely depend on their management methods. According to these management methods, these impacts result in either a decrease in flow rate change (derivation regimes) or an increase in this rate change (the other two regimes). In general, our study has shown that in Quebec, the impacts of dams generally translate into an increase in flow rate change (spatial variability). This increase is particularly important downstream of dams which reverse natural hydrological regimes. In addition, a distinction must be made between spatial variability and temporal variability of flow rate change indices.
Comment #02
The introduction suggests that the study can contribute to a better understanding of the ecological impacts of dams. The final conclusion that operational management is of influence on the flow variability is in that light very, very meagre.
Overall, the manuscript fails to show that the study brings new insights that are of use for "restoring the ecological integrity of regulated rivers".
Response
We understand your disappointment. Our study is a hydrological analysis, not an ecohydrological one. Its objective was not to study the impacts of changes in flow variability on flora and fauna. Nevertheless, we added information in the conclusion on the impact of the change in this variability observed downstream of the Matawin dam on the number of species in wetlands and terrestrial areas in low flow channel.
Author Response File: Author Response.pdf
Reviewer 3 Report
The article presents an interesting case study to analyze the impacts of dam management methods on seasonal daily flow rate change downstream of three dams. The reviewer is of the opinion that the following comments should be addressed in the article:
Page 2 - line 51: Please include a table with the different methods for managing the regulated hydrological regimes of dams, together with main characteristics of each methods and pontentially pros and cons
Page 2 - line 71: Please state how the objective of this study are going to be achieved, how this goes beyond the current state of the art and why this information is beneficial to scientists, asset owners etc
Page 3 - line 99: ''It is a heavy dam'' - please correct this as dams are not characterised as 'heavy' or 'light' but based on ICOLD are characterised based on their height (>15m = large dams)
Page 3 - Please provide basic information about the type of dams (embankment, concrete?)
Page 12 - line 364: please correct to reservoir
Author Response
REVIEWER # 03 : RESPONSES TO COMMENTS
We thank the reviewer for his comments and suggestions.
The corrections made are highlighted in yellow in the revised manuscript.
Comment #01
The article presents an interesting case study to analyze the impacts of dam management methods on seasonal daily flow rate change downstream of three dams. The reviewer is of the opinion that the following comments should be addressed in the article:
Page 2 - line 51: Please include a table with the different methods for managing the regulated hydrological regimes of dams, together with main characteristics of each methods and pontentially pros and cons
Responses
This is a very relevant suggestion from the reviewer. However, responding to this request is well beyond the scope of this article for the following reasons:
- We must make an exhaustive inventory of regimes regulated in the world. This inventory goes well beyond the scope of this study.
- Once the inventory has been taken, the criteria used to define these regimes must be standardized because these criteria vary greatly from one study to another. This standardization of criteria goes well beyond the scope of this study.
- It is also necessary to make an inventory of the variables used to define the flow rate change and to standardize them in order to be able to compare them. This work is also beyond the scope of this study.
- It is also necessary to make an inventory of studies according to the time scales of analysis: hours, day, month, seasons, years, etc. Such an inventory requires a lot of work which is well beyond the scope of this article.
In conclusion, it is impossible to summarize this topic in one table.
Comment #02
Page 2 - line 71: Please state how the objective of this study are going to be achieved, how this goes beyond the current state of the art and why this information is beneficial to scientists, asset owners etc
Response
We have reformulated this objective and third objective by adding the requested information (see lines 70-83).
Comments #03
Page 3 - line 99: ''It is a heavy dam'' - please correct this as dams are not characterised as 'heavy' or 'light' but based on ICOLD are characterised based on their height (>15m = large dams)
Page 3 - Please provide basic information about the type of dams (embankment, concrete?)
Page 12 - line 364: please correct to reservoir
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Overall, I am sorry to say that I fail to see the significance and novelty of this study.
In addition, I have some concerns with the authors' responses. First of all, I do not quite agree that the authors state the reason that they use the climate variable of total rainfall in the correlation analysis just because they happen to have the variable. If they do not have the right variable they need, this may suggest that they should not endeavor to conduct the study. The wrong choice of variable may lead to misleading conclusions. The simple correlation analysis also fails to account for the interaction between temperature and precipitation.
Secondly, I do not quite agree with the authors' response to my comment 3. This statement is not supported by their analysis at all. It could not be fixed just by replacing can with could.
Thirdly, in their response to my comment 2, they state that other studies that they have already published on the impacts of dams on other flow characteristics fully justify the extrapolation of their results to other dams characterized by the same management methods in Quebec. I could not see the validity of this justification purely based on the statement.
Finally, the authors state that it is important to note that they are not analyzing the impacts of climate on the temporal variability of flow rate change indices but the influence of management methods on the relationship between these indices and climate variables. Since the authors are analyzing a long-term series, could they ignore the impact of climate change? In my opinion, studying the double impacts of human activities and climate change on the change in flow regime is where the value of this type of study lies in.
Author Response
REVIEWER #01
We would like to thank the reviewer once again for his constructed comments. In response to these comments, we have added new information highlighted in green in our text. We rejected some comments in setting out our arguments. We insist that our results meet our goals which were clearly defined in our article.
Responses to comments
Comment #01
Overall, I am sorry to say that I fail to see the significance and novelty of this study.
Response
We fully understand the position of the reviewer. There is a great divergence between its position and ours on the objectives pursued by our study. As we will demonstrate later, the reviewer evaluates our study according to his own objectives that he wants to assign to our study and not according to our own objectives that we defined in the article. It is not surprising that the reviewer does not find any significance or novelty in our study.
Comment #02
In addition, I have some concerns with the authors' responses. First of all, I do not quite agree that the authors state the reason that they use the climate variable of total rainfall in the correlation analysis just because they happen to have the variable. If they do not have the right variable they need, this may suggest that they should not endeavor to conduct the study. The wrong choice of variable may lead to misleading conclusions. The simple correlation analysis also fails to account for the interaction between temperature and precipitation.
Response
We remind the reviewer that from the outset, the objective of our study was not to explain the mechanisms by which precipitation and temperature influence the the flow rate change indices. Our objective was clearly mentioned in our study: to analyze how dam management methods influence the relationship between flow rate change indices and climatic variables. To further clarify our focus on this topic, we have added more information (lines 85-89) and changed the title of point 3.3.
Comment #03
Secondly, I do not quite agree with the authors' response to my comment 3. This statement is not supported by their analysis at all. It could not be fixed just by replacing can with could.
Response
This is not a statement. This is a simple working hypothesis that we have set out for our next work. That’s why it’s in the conclusion.
Comment #04
Thirdly, in their response to my comment 2, they state that other studies that they have already published on the impacts of dams on other flow characteristics fully justify the extrapolation of their results to other dams characterized by the same management methods in Quebec. I could not see the validity of this justification purely based on the statement.
Response
In this work, we have clearly demonstrated that all dams subject to the same management mode induce the same hydrological impacts.Can the reviewer show us the opposite: two dams rigorously subject to the same management method can have totally different hydrological impacts?
Comment #06
Finally, the authors state that it is important to note that they are not analyzing the impacts of climate on the temporal variability of flow rate change indices but the influence of management methods on the relationship between these indices and climate variables. Since the authors are analyzing a long-term series, could they ignore the impact of climate change? In my opinion, studying the double impacts of human activities and climate change on the change in flow regime is where the value of this type of study lies in.
Responses
- The second objective of our study has been clearly defined: to determine the influence of dam management methods on the stationarity of flow variability indices. We are adding more information to clarify this goal.
- We compared the stationarity of hydrological series in natural rivers and downstream from dams. In natural rivers, the stationarity of the hydrological series is exclusively influenced by the climate. Therefore, by comparing the stationarity of the series in natural rivers and downstream of the dams, we also indirectly analyzed the influence of climate on the stationarity of the hydrological series downstream of the dams. Our results clearly demonstrate this influence of the climate in the L’Assomption river basin, whereas this influence is totally absent downstream of the Matawin dam due to the management method of this dam. It follows that we have taken into account the influence of climate on the interannual variability of the flow rate change indices downstream of the dams.
Reviewer 2 Report
The responses to the comments and the changes made in the manuscript are sufficient.
Author Response
Not reply
Round 3
Reviewer 1 Report
I am sorry to say that I still fail to find the significance and novelty of this study. I still feel the wrong use of variables could compromise their analysis results. I suggest that the authors should clarify what statements are hypothesis even they are in the conclusion section. I think I will leave the editor to make the final decision.
Author Response
Comment #01
I am sorry to say that I still fail to find the significance and novelty of this study.
Response
Our response remains the same. Our article was not evaluated against the objectives clearly defined in our manuscript.
Comment #02
I still feel the wrong use of variables could compromise their analysis results.
Response
Daily fluctuations in water levels are influenced mainly by precipitation and temperature in Quebec. So these are not false climate variables. In addition, the objective pursued in relation to these variables is clearly defined in the manuscript.
Comment #03
I suggest that the authors should clarify what statements are hypothesis even they are in the conclusion section.
Response
We made this clarification by adding a new sentence even though it was not necessary.
Author Response File: Author Response.pdf
